I'm forever having to call a plumber to drain the water that keeps getting trapped between the tub liner and the cast iron tub- as the previous owner had a liner installed only on the tub portion. Bad idea...

Currently, I'm attempting to drain it myself by attempting to remove the flange. I purchaseda tub drain remover tool and it says that with the simple application of a wrench ----Not happening-Hercules couldn't budge this thing!What's the catch?